US Patent 8004720 Method for adaptively screening continuous tone originals

The invention relates to printing, to facsimile and publishing techniques, in particular to picture reproducing systems capable to form two optical parameter levels, only. Said invention makes it possible to increase a fine detail reproduction accuracy, in particular, strokes on a screen copy and to more fully use a printing resolution power. The inventive method consists in converting a continuous tone original represented by multilevel reflection values of the areas thereof into a screen copy consisting of dark and light elements by using two types of weight values of the copy elements, wherein the first weight values are distributed between the elements in a sequence independent of the tone modification behavior through the original areas, and in the second sequence according to the geometry of the fine details thereof, in forming the copy elements in such a way that they are dark or light according to results of comparison between the reflection values of the original areas and the weight values of the first and second types, in increasing the degree of use of the second weight values for the fine strokes of the original with respect to the use thereof for single interfaces, which divide the original into dark and light regions and in removing elements which are established in a dark form according to the first weight values inside the light strokes arranged on a dark background.